The invention relates to an electrical connector, and more particularly, to an electrical connector having contacts formed with press fit collars, seated and lightly held within sleeves formed in a removable insulator adapted to serve as a seating tool for press fitting the contacts into receiving apertures formed in a substrate.
For certain connector applications, it is desirable to press fit contacts directly into a mounting substrate, such as a printed circuit board backpanel, to support the contacts and hold them rigidly in a fixed configuration. This press fit approach is in contrast to that of molding or otherwise directly mounting the contacts within an insulative body. Although an insulative body may be used in both instances, in the latter, the insulator is the primary structural support for the contacts, and problems arise because the insulator cannot be removed after the connector is mounted to the substrate. In that instance, it is virtually impossible to remove individual ones of the contacts from within the molded insulator and/or mounting substrate for repair in the event one of the contacts is damaged.
Certain prior art approaches to press fitted contacts have heretofore relied upon rigid, transversely extending load bearing shoulders for receiving and rigidly withstanding a press fit insertion force from an insertion tool. The load bearing surface area of each shoulder has been dependent upon the hardness of the seating tool bearing surface and the magnitude of the force necessary for press fitting. The position and shape of these press fitting shoulders on the contact has also been dependent upon the contact configuration. For example, certain contacts have been constructed for being press fitted into apertures in a mounting substrate and subsequently covered by a layover insulative housing. One such contact, of the card edge connector type, is described in U.S. Pat. No. 3,671,917, issued to John P. Ammon and Frederick T. Inacker on June 20, 1972, and assigned to the assignee of the present invention. The contact set forth therein is characterized by a fragile, or delicate, upper mating portion; i.e., a portion not capable of withstanding an axial load of the magnitude necessary for press fit insertion. The necessary load bearing shoulder for press fitting such a contact is effectively constructed beneath the upper mating portion. Once the contacts are press fitted into apertures in a mounting substrate, such as a conventional printed circuit board backpanel, the insulative housing is snapped over the top thereof.
Prior art contacts not having delicate upper portions have also been adapted for press fit application; and moreover, have been adapted for receiving the press fit insertion force directly on the topmost portion thereof. Such a contact is described and claimed in copending U.S. Patent Application Ser. No. 460,932, filed by J. Preston Ammon on Apr. 15, 1974, entitled "Folded Electrical Contact" and assigned to the assignee of the present invention. The electrical connector, and method of assembly thereof utilizing the folded contact of that invention is also described and claimed in copending U.S. Patent Application Ser. No. 460,931, filed by J. Preston Ammon on Apr. 15, 1974, entitled "Low Profile Integrated Circuit Connector and Method" and assigned to the assignee of the present invention.
The upper mating portion of the contact described in those two even date applications comprises a socket, rigid in structure and adapted for receiving and withstanding a directly applied, top loaded, press fit insertion force. Of great advantage in this approach is the availability of the insulator itself for applying the press fit insertion force directly to the contacts. Such a design eliminates separate holding fixtures and seating tools for mounting the contacts in a substrate. Unfortunately, this particular press fit design approach does not lend itself to contacts having fragile upper mating portions, such as the card edge connector type.
Related prior art approaches to press fit contacts have also included the utilization of the insulative housing as contact holding fixtures. Generally, the insulative housing has sleeves formed therein for either lightly or tightly receiving the contacts therethrough. Lightly held contacts generally have a load bearing region for engaging a separate press fitting fixture formed of a material (such as steel) having a suitably high compressive strength for withstanding the high stress concentrations of the relatively small contact load bearing areas. Such a connector and method of assembly are described and claimed in copending U.S. Patent Application Ser. No. 534,442, filed by J. Preston Ammon on Dec. 19, 1974, entitled "Electrical Connector and Method of Assembly" and assigned to the assignee of the present invention. The contact of that invention is lightly held in the insulator while a portion protrudes through the top thereof, exposing a press fit shoulder region for engaging a metal press fit tool.
Certain prior art discrete connectors have included insulators adapted for tightly holding top loaded contacts in sleeves formed therein, and in certain instances, have been used as the seating tool for press fitting the contacts in this most advantageous manner. Such approaches are illustrated in U.S. Pat. No. 3,530,422, to David S. Goodman, entitled "Connector and Method for Attaching Same to Printed Circuit Board". The connector described in the Goodman patent, includes contacts have transverse shoulders which are top loaded down into slots in the insulator. The contact tails are pulled through to seat the contacts, and the lower portion of each contact is twisted 90.degree. to lock each contact into the insulator and to provide an abutting engagement between the insulator bottom and relatively large outwardly extending shoulders formed on the contact. The contacts can then be press fitted into apertures in a substrate by applying force to the top of the insulator; however, once the contacts have been fully press fitted, it is impossible to remove the insulator to expose individual ones of the contacts for repair. Further, the relatively large, outwardly extending press fitting shoulders required on the contact prevent the contacts from being mounted on relatively close spacings, e.g., on 100 mil centers.
A trend in the development of the substrate mounted connector art is that of using structures which include an insulator removable from around contacts rigidly mounted into a substrate. A principal reason for removable layover-insulators is repairability. An insulator which may be removed from around the press fitted contacts provides a means of access to those contacts and facilitates repairability. It is desirable to provide a connector with contacts having delicate upper mating portions, wherein the insulator can serve as a contact holding fixture and a press fitting tool and then be subsequently removable after the contacts are rigidly press fitted into a substrate. One problem in the design of such connectors is that the transfer of press fitting forces from the top of the insulator to each contact is aggravated by the fragile mating portions, generally characterized by upwardly extending blades or tines which are not adapted for engaging an insertion fixture or for withstanding axial loads of the magnitude necessary for press fitting.
The connector and method of the present invention is especially adapted for the improved fabrication, assembly and housing of contacts having fragile upper mating portions. The present connector and method overcome many of the disadvantages of the prior art by providing an insulative housing, which itself serves as the holding fixture and press fit tool for these contacts, and yet is removable therefrom after the contacts are rigidly installed in a substrate. In addition, the contacts may be simultaneously inserted, in their proper orientation, into the insulator sleeves, and lightly held in position so as to facilitate normal handling as a complete subassembly without the danger of the contacts falling out. Since the contacts are held within the insulator sleeves with less retention force than the press fitted contacts are held into the mounting substrate, the connector of the present invention permits ready removal of the insulator and replacement of individual contacts.